Gaseous electric discharge device



Aug. 28, 1934. M. PlRANl GASEOUS ELECTRIC DISCHARGE DEVICE Filed July 7,1931 INVENTOR WZwweZZy fiuwu BY ATTORNEY Patented Aug. 28, 1934 UNITEDSTATES GASEOUS ELECTRIC DISCHARGE DEVICE Marcello Pirani,Berlin-Wilmersdorf, Germany, assignor to General Electric Company, acorporation of New York Application July 7, 1931, Serial No. 549,271 InGermany July 26, 1930 7 Claims. (Cl. 176124) The present inventionrelates to gaseous electric discharge devices generally and moreparticularly the invention relates to means for starting into operationhot cathode, positive column discharge devices of the arc and. glowdischarge type similar to that described in co-pending applicationSerial Number 377,044, filed July 9, 1929, being the invention ofMarcello Pirani and Hans Ewest.

It is well known in the art that auxiliary electrodes placed in theregion of the main discharge supporting electrodes facilitate thestaring of gaseous electric discharge devices. Hitherto it has been thepractice in the art to establish a glow discharge between the auxiliaryelectrode and its respective main discharge supporting electrode toestablish the positive column discharge in such devices. The object ofthe present invention is to establish quickly and certainly the positivecolumn discharge in gaseous electric discharge devices of the typereferred to above.

The invention attains its object through the use of auxiliary electrodeswhich consist of grouped wires presenting a multiplicity of points andcontaining or being coated with an electron emitting material. Saidauxiliary electrodes are connected in the circuit in such manner thatthe electric discharge between them and their respective main electrodesis a multiplicity of short intense arc discharges which concentrate onthe points of the auxiliary electrodes and on spots of the mainelectrodes.

The intense arc discharges formed in accordance with this inventionbetween the auxiliary electrode and the main electrode cause a prolificemission of electrons and ions as the are discharges concentrated on thepoints of the wires of the auxiliary electrodes and on spots of the mainelectrodes rapidly heat these restricted areas to a high intensity.Because of this heavy emission of ions and electrons the main orpositive column discharge path is heavily and quickly ionized andtherefore the positive column discharge between the main electrodes isestablished quickly and certainly.

In the drawing accompanying and forming part of this specification anembodiment of the invention is shown in side elevation, the ends of thetube being in section to show the particular arrangement of theelectrodes.

Referring to the drawing the electric discharge device comprises acontainer 1 having therein any suitable gaseous atmosphere well known inthe art. Electrode leads 3 and 3' of the main discharge supportingelectrodes 4 and 4 are sealed into the stems of electrode chambers 2 and2', said electrodes 4 and 4' are maintained at a glowing temperatureduring the operation of the device by the operating current of saiddevice. Leads 3 and 3' are connected to the terminals 5 and 5 of analternating current source, or said leads 3 and 3' may be connected tothe secondary coil of a transformer if desired. Main electrode 4 is asolid, cylindrical body consisting of a sintered mixture of adifiicultly fusible metal such as tungsten, and an electron emissivematerial, such as the oxides of alkali metals, or earth alkali metals.Main electrode 4' consists of like materials and is a hollow, closedcylindrical body having an opening 7 in the direction of the positivecolumn discharge path. The auxiliary electrode ,6, comprising a brush offine metal wires coated with electron emissive material such as thatdescribed above, is adjacent the main electrode 4 and is so spaced withrelation thereto that a multiplicity of short, intense arc discharges iseasily established between said electrodes 4 and 6. The auxiliaryelectrode 6', comprising a group of fine wires coated with a materialsimilar to that of electrode 6, is placed in the interior of hollowelectrode 4' with the spread part thereof in the direction of theopening 7 in the back of said hollow electrode 4'. Said opening 7permits the ions and electrons emitted by said electrode 6 and theinterior of main electrode 4 under the influence of the arc dischargesbetween said electrodes 4 and 6' to diffuse over into the positivecolumn discharge path. Auxiliary electrode 6 is connected to currentlead 3' of main electrode 4' by lead 8 having a high resistance 9therein and similarly auxiliary electrode 6' is connected to lead 3 ofmain electrode 4 by lead 8' having therein a high resistance 9. A chokecoil 10 is connected into lead 3 to serve as a ballast resistance forthe electric discharge device as is well known in the art.

When current is first applied to the circuit described heretofore a glowdischarge first takes place between the main electrode 4 and theauxiliary electrode 6 and a similar discharge takes place between themain electrode 4' and the auxiliary electrode 6'. As the points of theauxiliary electrodes 6 and 6' and the surface of main electrodes 4 and4' become heated short, intense arc discharges take place whichconcentrate on the points of the auxiliary electrodes and on spots ofthe main electrodes. These restricted areas on the main electrodes andthe auxiliary electrodes are thus heated to a high intensity so thatthey emit a heavy stream of electrons and ions which diffuse over intothe positive column discharge path to heavily and quickly ionize saidpath. When the discharge path is sufliciently ionized the positivecolumn discharge is established as the resistance of the ionizedpositive column discharge path is then less than that of the resistances9 and 9'.

While I have shown and described a particular embodiment of my inventionit will be understood, of course, that numerous modifications,substitutions, and changes may be made in the form and details of thedevice without departure from the broad spirit and scope of theinvention, for example, the electron emitting electrodes may be of anysuitable shape and may be heated by any of the methods well known in theart as by a wrapped around heating filament; the auxiliary electrodesmay be supported in other ways in the region of the main electrodes; ifthe device is to operateon direct current a single auxiliary electrodeadjacent the cathode is sufficient.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An electric discharge device comprising a container, a gaseousatmosphere therein, a plurality of starting and operating electrodessealed therein, at least two of said electrodes supporting the positivecolumn discharge in said device and at least one of said electrodesbeing an auxiliary electrode and having a multiplicity of arc supportingpoints, the electric discharge between said first named electrode andthe auxiliary electrode being an arc discharge.

2. An electric discharge device comprising a container, a gaseousatmosphere therein, a plurality of starting and operating electrodessealed therein, at least one of said electrodes being a main dischargesupporting electrode and being electron emitting when heated and atleast one of said electrodes being an auxiliary electrode and having amultiplicity of are supporting points parallel to a face of said mainelectrode, the electric discharge between spots on said first namedelectrode and the points of the auxiliary electrode being a multiplicityof arc discharges to rapidly increase the temperature of spots on saidelectron emitting electrode to their operating temperature.

3. The method of starting a gasous electric discharge device having maindischarge supporting electrodes which are electron emitting when heatedwhich consists in establishing a multiplicity of arc discharges at atleast one of said electron emitting electrodes to cause it to initiatean electric discharge in the gas between the main electrodes.

4. An electric discharge device comprising a container, a gaseousatmosphere therein, a plurality of starting and operating electrodessealed therein, one of said electrodes being a hollow, main dischargesupporting electrode and having an aperture in one wall thereof, anotherof said electrodes being an auxiliary electrode mounted in said hollowelectrode and having a multiplicity of arc supporting points, theelectric discharge between said main discharge supporting electrode andsaid auxiliary electrode being an are discharge.

5. An electric discharge device comprising a container, a gaseousatmosphere therein, a plurality of starting and operating electrodessealed therein, one of said electrodes being a hollow, main dischargesupporting electrode, electron emitting when heated and having anaperture in one wall thereof, another of said electrodes being anauxiliary electrode mounted in said hollow electrode and having amultiplicity of arc supporting points, the electric discharge betweensaid main discharge supporting electrode and said auxiliary electrodebeing an arc discharge.

6. An electric discharge device comprising a container, a gaseousatmosphere therein, a plurality of starting and operating electrodessealed therein, one of said electrodes being a main discharge supportingelectrode, another of said electrodes being an auxiliary electrode andhaving a multiplicity of are discharge supporting points, both of saidelectrodes being electron emitting when heated, the electric dischargebetween said auxiliary electrode and said main electrode being amultiplicity of arc discharges to rapidly raise spots on said mainelectrode and the points on said auxiliary electrode to an electronemitting temperature.

7. An electric discharge device comprising a container, a gaseousatmosphere therein, a plurality of electrodes sealed therein, one ofsaid electrodes being a main discharge supporting electrode, another ofsaid electrodes being an auxiliary electrode comprising a multiplicityof discharge supporting points, the discharge between said auxiliaryelectrode and said main electrode being an auxiliary discharge tofacilitate the establishment of the main discharge in said device.

MARCELLO PIRANI.

